June 27  2000 Update
Now that the paint is done, time to work on the inside. First comes the stereo. It just makes sense to do this now, while the seats and everything else are out of the way.
The speaker cutouts in the rear deck were so roughly cut out that the rough edges would have ruined any speaker that I tried to install. About an hour on each side with a small grinding wheel and they are cleaned up.
 
 

There are a couple of problems with just mounting the speakers in the trunk like most people do. Whenever you slam the trunklid closed the speaker cones get forced up by the air pressure in the trunk, and they can be ruined that way.
Also, speakers that are mounted in proper speaker cabinets just sound better than ones that are installed in the trunk.  So I set out to find some pre made cabinets. All of the cabinets that I found were too deep for the trunk, I would not have been able to keep the spare tire in its correct location in the trunk.  So I decided to make my own speaker cabinets. This way, I could make them shallower than the pre built cabinets, and also make them larger, which will give better sound quality.

After doing a little bit of measuring, I came up with the design that you see here. This has plenty of clearance in the trunk, in fact I could have made them a little bit bigger, and I would make them bigger if I was going to make another set.
I started out by buying two pieces of 5/8 inch particle board, 24 x 48 inches. I don't have a table saw, so I had the home supply store cut up the wood for me. They charged me 50 cents per cut, which came out a lot cheaper than a table saw, but they did not do a very good job. The total cost of materials and the charge for materials and labor was only about $25.00 for the whole project. I glued the pieces together with white glue, and drove in some finish nails to hold the boxes tightly together while the glue dried.

Next I traced the outline of the holes on the front of the boxes, using a piece of plastic that normally goes under the speaker grilles as a template. I cut out the holes with a jigsaw. I also put a small hole in the back of the box for some radio shack speaker wire terminals. I had some black cloth that I got from the upholstery shop for the rear deck. I sprayed aerosol glue all over the cabinets and rolled them up in the fabric. Basically, I wrapped the boxes up in the cloth as if they were Christmas presents. Then I used the staple gun to fasten down the edges of the cloth. The finished result looks like a professional job. I picked out some JBL GTO920 speakers from the Crutchfield catalog, and mounted them in the box with wood screws.

I set them up in the living room to see how they sounded, and to make sure they work. They sounded very bright, way too much treble. I was also kind of disappointed that there was not much bass.  But lets put them in the car and see how they sound. I drilled some holes, and put the speakers into the rear deck with large sheet metal screws. I used six screws per side, so these speakers are not going anywhere. I put some thick weather-stripping between the the boxes and the rear deck, to prevent any rattling. The installation was pretty tricky. I ended up putting a floor jack into the trunk, and using that to push the speaker boxes up against the rear deck,  so that I could get the screws in from inside the car. And how do they sound? Ahhh, much better. The bass is back, with much better balance between the low and high frequencies.